Its not possible to get a 200ul dilution at 10ng/ul from 3 ul of your stock DNA. 200ul at 10ng/ul means you have a total of 2000ng, while you only have 3ul at 280ng/ul, or 840 ng total DNA to start with. if you dilute your sample to a total of 84ul (add 81ul) then you will have 10ng/ul, but only 84 ul of it.

Its not possible to get a 200ul dilution at 10ng/ul from 3 ul of your stock DNA. 200ul at 10ng/ul means you have a total of 2000ng, while you only have 3ul at 280ng/ul, or 840 ng total DNA to start with. if you dilute your sample to a total of 84ul (add 81ul) then you will have 10ng/ul, but only 84 ul of it.

Thanks. I would like a bit more volume than 84ul. I can also bring the final concentration down to between 4-5ng/ul. I have tried this math:

Its not possible to get a 200ul dilution at 10ng/ul from 3 ul of your stock DNA. 200ul at 10ng/ul means you have a total of 2000ng, while you only have 3ul at 280ng/ul, or 840 ng total DNA to start with. if you dilute your sample to a total of 84ul (add 81ul) then you will have 10ng/ul, but only 84 ul of it.

Thanks. I would like a bit more volume than 84ul. I can also bring the final concentration down to between 4-5ng/ul. I have tried this math:

thanks for checking. one last question, how do I use your method to make up the amount that I did? I know what you had done (3ul/84ul)*280ng/ul = 10ng/ul, but couldn't figure out how you got 81 in the first place. What formula did you use?

thanks for checking. one last question, how do I use your method to make up the amount that I did? I know what you had done (3ul/84ul)*280ng/ul = 10ng/ul, but couldn't figure out how you got 81 in the first place. What formula did you use?

there was no formula. the equation will give you the total volume (84ul). since you already have your DNA in a total of 3ul volume, you need to add 81ul to make the 84ul final volume. (84ul-3ul=81ul)